1. Field of the Invention
The present invention is related to a sidewall image transfer (SIT) process, and more particularly, to a SIT process that comprises an automatic process control (APC) ability.
2. Description of the Prior Art
In modern society, the micro-processor systems comprising integrated circuits (IC) are ubiquitous devices, which are utilized in diverse fields such as automatic control electronics, mobile communication devices and personal computers. With the development of technologies and the increasingly imaginative applications of the electrical products, the IC devices become smaller, more delicate and more diversified.
For scaling down the size of the metal oxide semiconductor transistors (MOS), three-dimensional or non-planar transistor technology, such as fin field effect transistor (Fin-FET) technology has been developed to replace the planar MOS transistors. In current techniques, in order to meet the sub-lithographic requirements, a regular photolithography and an etching process are provided to form fin structures in the Fin-FETs. Additionally, semiconductor device manufacturers also utilize a pattern transfer technique, such as the sidewall image transfer (SIT) to form required fin structures.
However, since the CD of the fin structures is becoming smaller, many problems are met during the manufacturing process. Therefore, there is still a need for a novel SIT processes that can meet the CD requirement and reduce the manufacturing errors, so as to upgrade the yield of the products.